It’s Windows 8 if by Intel, Windows RT if by ARM

Microsoft has chosen the brand names under which it will sell Windows 8, the company’s most important product launch in a generation. There’s good news and bad news: Microsoft has smartly cut down on the number of versions that consumers and businesses will have to choose between, but it has chosen to give its first ARM-friendly operating system a weird name, perhaps in deference to an old friend.

The three brand names for Windows 8 were announced late Monday on Microsoft’s corporate blog. Traditional Intel or AMD-based PCs will be available under the Windows 8 and Windows 8 Pro brands. But Intel-based tablets will also be available as “Windows 8″ devices, while tablets based on chips designed by ARM will be called “Windows RT,” a name that had bloggers and tech enthusiasts squawking within minutes of its release.

Given that Microsoft has invested the bulk of its industry promotion thus far around the Windows 8 brand, it’s quite surprising that the ARM-based tablets–perhaps Microsoft’s best shot at breaking into the mobile computing market dominated by its old nemesis Apple–will carry a strange-sounding brand that has no relation to Windows 8.

That’s ripe for confusion: to be clear, not as much as surrounded previous launches of Windows, which came with as many as six different versions, all with different features. But Windows RT appears to refer to the name for the APIs that accompany Windows 8–Win RT–and that could be a confusing thing for retail consumer electronics employees to explain when asked to compare the relative merits of a Windows 8 tablet and a Windows RT tablet.

Windows 8-branded devices, however, will have a “Desktop” feature that will allow users of those devices to run older Windows 7 applications: something the Windows RT devices lack. So that makes some sense: Windows 8 is the sequel to Windows 7, while Windows RT is something new that won’t work with your old Windows programs.

But this a boost for Microsoft’s old frenemy Intel, which has a history of meddling in Microsoft’s branding decisions to suit its own needs. Intel and its partners will be able to associate their mobile products with the overarching “Windows 8″ brand, while ARM partners will have to do more heavy lifting to promote the merits of their products.